Stone throwing protesters have clashed with police in Hamburg after a rally by supporters of the far-right National Democratic Party (NPD).At least two people were arrested near the city’s main train station. Riot police backed by water cannon, dispersed the crowd. There have been no reports of any injuries. A spokesman for the police said officers had to “fire one or two warning shots” when left-wing protesters hurled stones and bottles at police and attacked a squad car. Earlier some 3,500 people had demonstrated peacefully against the right-wing rally. Police stepped in to keep the two groups apart. The NPD supporters, said to have numbered less than 100, were demonstrating against an annual multicultural street festival known as the “Schanzenfest” which led to clashes between extremists from the left and right last year.